Hi! I'm building a portable solar generator for RV dry camping with my family, and need some help sizing the charge controller, and validating my findings so far. Basically, my needs are to be able to run a couple small fans, charge devices, and intermittently plug in small appliances as needed for long weekends and the occasional weeklong trip.
Currently planned major components:
- 100Ah LiFePO4 battery (one to start, but potentially expand to two if needed)
- SmartSolar 75/15 MPPT
- 500-700W inverter
- 100W Solar panel (Potentially want to expand out to 200-400W in the future)
- Multi stage trickle charger
Here is my wiring diagram: https://imgur.com/a/MgqJaGU
Questions:
- If I start off with only 100W worth of solar (these panels are expensive!), will the 75/15 still charge my battery? Or do certain charge controllers require a minimum solar size to actually charge a battery? I realize I need ~240W to fully charge my 100Ah battery in one day, but I am not going on super long trips to start, and can top off at home with a trickle charger
- (See my wiring diagram) - is there any risk in damaging the charge controller by using the trickle charger while the MPPT charge controller is attached? For ease of use, I'd like to be able to leave the battery in place and charge via an SAE port that I'd attach to the same bus bar that the battery / charge controller / inverter are attached to. I wasn't sure if there was any risk of back flow or whatever
- Given everything above, does the 75/15 MPPT still sound right, or should I upgrade (100/20) or downgrade (75/10)? It sounds like if I wanted to scale out to a two-battery system, the 100/20 would be better, but given I want to start small, I'm wondering if I should think about replacement when it gets to that point instead of trying to over-future-proof my system
Open to any and all feedback. I was largely inspired by Jim Fisher's setup: https://www.youtube.com/watch?v=offgcMwuTGw&t=300s
Thank you!